Role of Dynamic Flexibility in Computing Solvatochromic Properties of Dye-Solvent Systems: o-Betaine in Water
2009 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 113, no 11, 2572-2577 p.Article in journal (Refereed) Published
Car-Parrinello molecular dynamics (CPMD) and Car-Parrinello mixed quantum mechanics/classical mechanics (CP-QM/MM) calculations were performed for o-betaine (OB) in the gas phase and water as solvent to study the solvent dependence on its molecular properties: geometry, charge distribution, and dipole moment. It is found that the molecular geometry in the gas phase is close to the planar structure, while in the water it is a twisted structure. The calculations clearly show that in both the gas phase and water the OB molecule is highly flexible with a large amplitude for the twist angle motion. The average gas-phase dipole moment for OB doubles in water, something that concords with a strong increase of total charge on phenoxide and pyridinium rings. We also investigated the solvatochromic shift in the pi-pi* and n-pi* transitions by carrying out INDO/CIS calculations for the gas-phase and solution-phase configurations obtained from the CPMD and CP-QM/MM calculations with results that are in good agreement with available experimental values (J. Chem. Soc., Perkin Trans. 2 1999, 1, 713). Our work indicates the importance of allowing full structural and dynamic flexibility of dye-solvent systems in predicting their basic solvatochromic properties.
Place, publisher, year, edition, pages
2009. Vol. 113, no 11, 2572-2577 p.
molecular-dynamics, polarity indicators, simulations, mechanics, density
IdentifiersURN: urn:nbn:se:kth:diva-18238DOI: 10.1021/jp8097395ISI: 000264111000040ScopusID: 2-s2.0-64349108110OAI: oai:DiVA.org:kth-18238DiVA: diva2:336284
QC 201005252010-08-052010-08-052013-03-14Bibliographically approved